In a typical skylight arrangement, a hole is cut into a roof of a building and a clear dome is installed, thereby allowing natural light to enter the building. Incorporating a skylight system into a building which includes an attic (or other spacing between the outside of the building and the room which is to receive the light) most often requires a tubular skylight system. A tubular skylight system typically allows natural light to pass through a clear outer dome, reflect in a cylindrical light tube that spans the height of the attic space, then enter the room through a diffuser (see FIG. 1).
During the summer months, in most places, an adequate amount of light enters the skylight system because the sun is substantially above the clear outer dome, thus allowing direct rays of sun to enter the cylindrical light tube. However, during the winter months, the sun's rays often perpendicularly intersect the sides of the clear outer dome, thereby forcing a large portion of the rays to go directly through the outer dome without ever entering the cylindrical light tube. To deflect a large portion of the substantially perpendicular rays down into the light tube, many of the present tubular skylight systems incorporate a reflective material on the inside surface of the clear outer dome. However, installing a reflector onto the clear outer dome typically results in a large portion of the clear outer dome (ie., approximately 1/3 of the surface area of the dome) being covered by the reflective material. Consequently, during summer months, certain of the sun's rays would often intersect the backside of the reflective material and be restricted from entering the light tube, thereby reducing the amount of light entering the enclosed building.
Tubular skylight systems typically include a flashing which is secured to the outside surface of the roof. The flashing is often designed such that the light tube is reciprocally received through the inside of the cylindrical extension of the flashing and a clear outer dome is secured to the top end of the flashing (see FIG. 1). Fastening the outer dome directly to the flashing often prevents the escape of heat or condensation which typically builds up inside the tubular skylight system. Moreover, when securing the outer dome to the flashing, prior art systems often incorporate screws or bolts which, upon installation or over time, tend to crack the outer dome from the point pressure.
The light tube typically extends from the top of the flashing down to the top of the inner ceiling of the building. The lower end of the light tube (the end which abuts the inner ceiling) typically sits on the top surface of the inner ceiling (see FIG. 1). Consequently, the light tube is often rigidly secured between the inner ceiling and the flashing, thereby rigidly isolating the flashing from movement. Because of the rigidity of the flashing, when snow collects on the roof surface and forces the roof to sag slightly downward, the entire tubular skylight system is often forced upward and away from the outer roof allowing the entry of air, water and pests into the attic. Additionally, when replacing roof shingles, the flashing is typically lifted such that the shingles can be properly placed underneath the flashing. However, because of the rigidity of prior art systems, lifting of the flashing would require the difficult disassembly of the outer dome and light tube.
Furthermore, the abutment of the lower end of the light tube on the top surface of the inner ceiling (see FIG. 1) often provides unwanted collimation of the entering sunlight rays due to the side surface of the opening in the inner ceiling. Additionally, due to the placement of the lower end of the light tube on the top surface of the inner ceiling, to avoid the entry/exit of light rays or the entry/exit of unwanted air or bugs, the light tube is typically required to be set substantially perpendicular to the surface of the inner ceiling.